gr-iridium is free software to capture and demodulate data from the Iridium satellite network. This talk dives under the hood of gr-iridium and shows how it can capture and demodulate 1000 frames per second on an 8 year old quad core machine.
Iridium was launched at the end of the 90s. Back in the day it was considered extremely difficult to intercept because of the large bandwidth and constantly changing doppler shift. With the rise of Software Defined Radio and more capable general purpose computers this is not the case any more.
This talk dives deeper into the structure of gr-iridium and shows how GNURadio can be used to receive very bursty and fast changing signals, something it is traditionally not very good at. It will also give you some basic understanding of the math behind demodulating a PSK signal in complex baseband.
It will not cover the higher layer parts of our work on Iridium. If you are interested you can always have a look at our presentations at HOPE (https://www.youtube.com/watch?v=cvKaC4pNvck) and 33C3 (https://media.ccc.de/v/32c3-7154-iridium_update)